GENERAL METHODS: Method B: To a stirred solution of 1-(2,3-dihydrobenzo[B][1,4]dioxin-6-yl)ethan-1-ol (4a, 1.65 g, 9.94 mmol) in anhydrous dichloromethane (100 mL) was added Dess-Martin's reagent (5.06 g, 11.93 mmol) at 0 °C and under argon protection. After 10 minutes of reaction, the mixture was slowly warmed to room temperature and stirring was continued for 16 hours. After completion of the reaction, the reaction was quenched with saturated sodium bicarbonate solution and filtered to remove the insoluble salt. The filtrate was extracted with dichloromethane, the combined organic layers were dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. Finally, the target product 6-acetyl-1,4-benzodioxane (5a, 1.42 g, 87% yield) was purified by silica gel column chromatography with dichloromethane as eluent to give a light yellow solid.
